My MT racer came with that clutch and I put one in my Nitro Rush and I like it. It is adjustable to where you can set it to come on at different RPM. The only problem is you have to cut it to do so and once you do that you are stuck with what you have. As far as a 15 tooth clutch bell depends where you run and what type of running you do. For me that is too tall of a gear. Will give you better top end at sacrificing torque and bottom end.